Cleaned Up Godot Assets Structure

[BrickPi]

• Added Application Icons for Windows, Mac, and Linux
• Localised "Asset Path Not Found" message box and reworded message to be less technical.
• Moved localisation to assets/localisation
• Moved audio to assets/audio
• Removed legacy assets from repo pending custom mode, still retained in Google Drive.
• Moved quotes.txt and credits.csv to assets/localisation
• Removed unused assets in common
• Moved theme to assets/graphics/theme
• Moved used assets under art to assets/graphics

All suggestions are welcome.

Open to extending reorganisation to the src folder to reflect new needs after pivoting to compatibility.

Eventually will need to refactor credits to better reflect organisation of project and accretion of new contributors.

All modified features tested and working. :-)

[Spartan322]

Linux crashes with WARNING: Icon too large, attempting to resize icon.

[Spartan322]

Something is seriously wrong with running the files built on Ubuntu with Arch Linux.

[Hop311]

When I exported locally and tried running the exe, the whole screen would get a white tint, like when a program stops responding, and then just stopped, so something's broken (this was yesterday morning, I'll try again with the recent changes later today).

[BrickPi]

Everything should finally be fixed and working 😭